Centre for Research, Education and Training in Energy

Category Archives: Green Energy

Many areas of the recycling industry attract rumours, counter rumours, truths and untruths which tend to overshadow the real benefits of recycling. We will now take a look at what happens to your recycled waste once it is picked up and how it can be recycled into everyday items.

Recycling bins

In the UK we have individual recycling bins for plastic, glass and other waste products which are collected by the local authorities. The situation can be slightly different in some areas of the world which can use a process known as “single stream recycling” where there is no need to separate paper, plastic and glass as this will be done automatically further down the line. It can be annoying having to split all of your waste into individual bins but the benefits to the climate and indeed the growth in the recycling industry are there for all to see.

The separation process

We will look at the separation process with regards to the “single stream recycling” process as this will give you an idea of how advanced and complex the recycling industry has become.

When the waste is collected it will arrive at what is known as a “materials recovery facility” where the separation process begins. The process itself looks and sounds very simple but it is extremely focused and able to separate all kinds of material in an automated fashion.

Separating paper

All of the waste is placed on a conveyor belt which is structured in such a way to ensure that heavier items such as glass, plastic and metal fall through holes in the initial conveyor belt and are caught on another belt below. This separates all paper, cardboard and newspaper which will be batched and recycled.

Magnetic metals

Once the paper has been stripped out then magnetic metals are next on the list with huge magnets hovering above the conveyor belt simply lifting metal products and placing them in a bin for recycling. This simple process is extremely effective and ensures that no ferrous metals make it to the next stage.

Non-magnetic metals

This is perhaps the most interesting stage of the separation process. Using what is known as an “eddy current rotor” material such as aluminium are charged with electricity which causes them to shoot away from other materials on the conveyor belt to be collected in a separate bin. Simple but ingenious!

Separating plastic

Using an optical scanner the machine is able to differentiate between plastic and glass, funnelling all plastic products into a separate bin using “a blast of air” to fire them off the conveyor belt.

Glass

Now that all other materials have been separated all we are left with is glass and the separation process is complete.

Recycling individual materials

As we touched on above, some local authorities will make you separate your waste before collection while others will use the single stream system. However, at some point they will all arrive at the next stage of the recycling process which involves manipulating individual materials into a form in which they can be recycled and reused.

Recycling paper

The key here is to recycle all paper into pulp which is the most basic form of paper from which an array of different products can be made. All paper which arrives at the paper mill is loaded into a de-inker machine which is a chemical washing process that separates the paper from the ink. This creates pulp slurry which is then loaded into a large industrial washing machine which spins at excessively high speeds and removes unwanted particles such as string and glue. The paper pulp is then transferred to a press and ends up on giant paper rolls which are used by industry.

Recycling metals

The individual types of metals, ferrous and non-ferrous, are transferred to metal mills where they are heated to extreme temperatures at which point they become a molten liquid. This liquid is then placed into ingot moulds which can then be used to create anything from filing cabinets to tinfoil and even large structures such as bridges.

Recycling plastics

The plastics recycling process is slightly more complicated because as you will see next time you look at the bottom of a plastic bottle or other plastic product, they are all numbered. This number relates to a specific type of plastic with example the most common found in water bottles and juice bottles. Each different variation of plastic is separated and then sent along a conveyor belt with a grinding machine which cuts and chops the plastic into the very fine plastic flakes. These flakes are melted down to create a polymer which is then used to create an array of everyday items such as rubbish bins, etc.

Recycling glass

There is no filtering of different sized glass products as they are all placed on a conveyor belt and crushed into tiny elements called “cullet”. The cullet is then either sent direct to manufacturers in its basic form or turned into molten glass and used to create numerous everyday items such as floor tiles, garden ornaments, glass door knobs and even beaded jewellery.

Selling recyclable waste overseas

One of the most common rumours hanging over the recycling process is the idea that waste is sold to countries such as China which often have a shortage of natural resources. The truth is that countries such as China do pay good money for recyclable waste which is transported in large container ships. Once they reach their destination the recycling process begins………………